Paths from `--lib` should be absolute
Paths from `--lib` should be absolute

Summary:
Lib paths are supposed to be absolute, but we libs comming from
the commandline via `--lib` weren't absolute.

Reviewed By: samwgoldman

Differential Revision: D6550438

fbshipit-source-id: 64bf4d96a04b4bb34c7b95e6e32fa8c38ba94fb6

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